Debt and Credit Arrangements Capped Call (Details) (4.75% Notes, USD $) In Millions, except Per Share data, unless otherwise specified	12 Months Ended
Dec. 31, 2011	Dec. 31, 2010
4.75% Notes
Debt Instrument
Capped call, strike price	$ 12.13	$ 12.42
Capped call, cap price	$ 17.83	$ 18.26
Capped call, number of shares that may be purchased	16.5
Capped call, expiration date	Apr. 02, 2013
Capped call, cost of options		$ 22.8

The cap rate on a price risk derivative such as a cap or collar. A payment or receipt is triggered if the market rate exceeds the cap rate on the contract.

No definition available.

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